1. Field of the Invention
This invention relates to the extraction of dirt from surfaces such as carpet and bare floors. In another of its aspects, the invention relates to an extraction cleaning machine that applies a heated cleaning fluid to a surface to be cleaned with a minimum of heat loss prior to application to the surface. In another of its aspects, the invention relates to an extraction cleaning machine which is adapted to heat a cleaning fluid in close proximity to a surface to be cleaned. In another of its aspects, the invention relates to a mop that generates steam in close proximity to the surface to be cleaned. In yet another of its aspects, the invention relates to a method for extracting dirt from a surface to be cleaned by heating a cleaning fluid in close proximity to a surface to be cleaned to minimize heat loss between the time the cleaning fluid is heated and the time that the cleaning fluid is applied to the surface to be cleaned.
2. Description of the Related Art
Upright extraction cleaning machines have been used for removing dirt from surfaces such as carpeting and rugs. The known extraction cleaning machines can be in the form of a canister-type unit, as disclosed in U.S. Pat. No. 5,237,720 to Blase et al., or an upright unit, as disclosed in U.S. Pat. No. 6,131,237 to Kasper et al., both of which are incorporated herein by reference.
Both types of units contain a fluid delivery system for depositing a quantity of cleaning fluid on the carpet surface. The cleaning fluid dissolves the dirt, removes the dirt from the carpet fibers, and places the dirt in suspension, which aids in the extraction of dirt from the carpet. The cleaning fluid is typically dispensed on the carpet through one or more dispensers, such as spray nozzles, in the extraction cleaning machine where it can be worked into the carpet by one or more rotating brush-type agitators.
U.S. Pat. No. 6,131,237 to Kasper et al. discloses heating a cleaning fluid with an in-line heater between a cleaning fluid solution tank and the cleaning fluid dispenser. It is also known to heat cleaning solution with an immersion heater located in the solution tank, prior to depositing the cleaning fluid on the surface. Both types of heaters are generally located in the cleaning machine at a point somewhat removed from the cleaning fluid dispenser. The dispenser spray nozzles are frequently located in an upper wall of a chamber that encloses the rotating brushes. Thus, the cleaning fluid must pass through the chamber to contact the carpet surface. Cooling of the heated cleaning fluid can occur during the time that the cleaning fluid travels from the heater to the fluid dispenser. Additional cooling can occur as the cleaning fluid passes through the chamber to the carpet. This cooling can reduce the cleaning effectiveness of the cleaning fluid. Kasper et al. also disclose heating a cleaning solution in an in-line heater that is in a cleaning head attached to a wand that is connected to a canister extraction unit.
Increasing the temperature of the cleaning fluid in a conventional extractor is limited by the power available to generate heat and the potential for the cleaning fluid to overheat, pressurize, and damage the cleaning fluid delivery system. In-line heaters also suffer from clogging as a result of the buildup of sediment and other residues. Tank heaters can be slow to heat the cleaning fluid, and the tank must typically be insulated, thereby adding volume and weight to the cleaning machine.
Further, the carpet is relatively cool with respect to the heated cleaning fluid and thus extracts heat from the heated cleaning fluid as it is applied to the carpet surface, thereby diminishing the cleaning power of the cleaning solution. This problem may be overcome somewhat by raising the temperature of the cleaning solution. However, in conventional domestic carpet extractors, the power to continuously raise the temperature of the cleaning solution is limited by domestic circuits in the United States and Canada. Further, the volume of cleaning solution with respect to the area of the carpet is relatively small so that the cleaning solution has limited ability to raise the temperature of the carpet to limit the cooling of the heated cleaning solution as it is applied to the carpet.
Steam generating machines have been used to clean and sanitize hard-surface floors. Known steam machines can be in portable hand-held form or in the form of an upright machine. An example of a commercially-available stick-type upright steam machine is marketed by BISSELL Homecare, Inc. under the name Steam Mop™. All of the known prior art locates the steam generator remote from the dispensing opening.
The effectiveness of the cleaning process can be enhanced by using an extractor that can heat the cleaning fluid immediately prior to its application to the carpet or hard-surface floor.